Neural mechanism of embodied emotion and its influence on decision making

Abstract

The close link between emotion and somatic responses has been emphasized in many previous theories including the hypothesis of William James to the recent Somatic Marker hypothesis. Those theories suggested that our emotion arises from an interoceptive processing of our bodily signal and would consequently influence our behavior. However, mechanisms underlying "embodied" emotion and how this embodied emotion influences our decision has rarely been investigated. In my studies, I aimed to investigate 1) an interoceptive processing during an emotion processing using heartbeat-evoked responses and 2) how this embodied emotion influences our decision making under uncertainty. In current studies of mechanisms underlying embodied emotion, I found out that an interoceptive processing within the salience network from right anterior insula to cingulate cortex increases during an transient emotion processing induced by emotional faces. Furthermore, in the second study, I found out that there exist a cortical theta-synchronized network that processes heartbeat and the synchronization within this network is related to a persistent mood state of an individual. In the studies regarding an influence of embodied emotion on decision making under uncertainty, participants performed a decision making task under uncertainty where their emotional state during decision has been modulated by a probabilistic threat. In the first study, I found out that in the face of highly probable threat, an influence of uncertainty inference on decision has been controlled via the medial prefrontal cortex. Furthermore, in the second study, I found out that decision making in those situation involved two pathways – a direct pathway that controls behavior without involving conscious emotion and an indirect pathway which influences behavior via inducing conscious fear. Interoceptive processing mediated a latter pathway of generating conscious fear and consequently interefered with a behavior control process. In other words, in this study, we found out that an embodied conscious fear interferes with a behavior control process during decision making. In summary, I found our that a cortical network level processing of interoception influenced an transient or persistent embodied emotion and this embodied emotion processing interacted with a behavioral control process during decision under uncertainty. These results provided a specific mechanism regarding a role of interoceptive processing in emotion, which mechanism has been thought to have a fundamental importance in understanding emotion and it also provided how this embodied emotion consequently influences our behavior. We hope that these results might provide an important clue to understanding pathophysiology of affective disorders and its treatment.